By analyzing structure-borne noise, it is possible to identify features which assist in the detection of faults or errors in mechanical, electromechanical or fluidic components. For example, EP 1 216 375 B1 discloses a diagnosis system for a valve which can be activated by a position adjuster via a drive mechanism, in which the intensity of the structure-borne noise in a spectral range above 50 kHz is used for detecting a leakage in the valve. However, the known diagnosis system requires a spectral analysis of the measurement signal and hence a considerable expense in terms of electronics and computing power. This also involves an increase in the electrical power consumption of the analysis entity. Integration of the diagnosis method as an additional function in existing devices is therefore seldom possible, since the additional power is often unavailable. In particular, this applies to field devices of automation systems, e.g. measurement transformers or control elements. These must satisfy explosion protection requirements in many cases, or are supplied with the necessary auxiliary energy via a 4 to 20 mA interface or a PROFIBUS connection. The diagnosis system must then be housed in an additional device at additional expense.
U.S. Pat. No. 5,477,729 discloses a sensor for structure-borne noise, which sensor is suitable for measuring high-frequency acoustic signals up to approximately 2 MHz.